The military has had a long standing need for protective clothing which would protect the wearer from toxic chemical agents. Currently, there are two mechanisms by which a textile material may afford protection against chemical agents. One mechanism is sorption, which has been provided by carbon-treated foams and non-woven fabrics. The other mechanism is chemical deactivation, which is presently provided by chloroamide-treated clothing items. The sorptive charcoal in current protective garments does not neutralize chemical agents but merely sorbs them. Sorptive charcoal therefore presents a potential problem of subsequent desorption. The chloroamides used in chemical deactivation readily liberate hypochlorite in the presence of moisture and chloroamide-treated clothing causes severe skin irritation in some individuals. In addition, clothing which has been treated with chloroamides gradually loses its effectiveness and requires periodic retreatments.
Many bulk reagents have been effective neutralizers and decontaminants for chemical warfare agents. Current storable formulations are based upon strong-base reagent combinations such as lithium hydroxide in monoethanolamine (MEA) and sodium hydroxide and diethylenetriamine in methyl cellulose. Unstable formulations such as sodium and calcium hypochlorite (chlorox and HTH) are also effective. Hydroxamic acids, oximes, phenols, and metal-ion complexes are all effective in promoting the deactivation of chemical agents in aqueous solutions. However, none of the bulk chemicals have been suitably formulated for application to fabrics to provide protective clothing.
Microcapsules have been used in numerous other applications to separate active ingredients, to control odor, to mask taste, to control volatility and flammability, to moderate chemical reactivity, to provide slow release of contents and to protect the environment. In particular, microcapsules of sodium hydroxide have been used to remove phenols and organic acids from refinery waste water; microcapsules containing organic solvents have been used to remove MEA from aqueous solutions and microcapsules of methyl parathion within semipermeable nylon are marketed as controlled-release pesticides.
The present invention has overcome the disadvantages of prior protective clothing through development of agent-reactive microcapsules that can be applied to fabrics or finished garments to provide reactive sites for neutralization of chemical agents. Specifically, the invention involves microencapsulation of conventional decontamination chemicals that are currently effective for deactivation of toxic mustard blistering agents (H agents); and toxic nerve agents known conventionally as G agents, e.g., isopropyl methyl phosphonofluoridate (GB, sarin) and the V agents, e.g., VX and formulation of the microcapsules in a resin finish that can be uniformly applied to fabric substrates.